Give it to me straight: suspension/alignment setup
 

I need some help guys. In spite of having invested heavily in the suspension setup on my '81, something isn't quite working for me. Part of this is definitely the inadequate driver, so lets factor in for that.

The hard specs are like this:

• Full deal from Elephant Racing. Monoballs, Sphericals, Polybronze in the rear, 21/28mm torsion bars, Carrera sway bars, Bilstein dampers, 30mm raised spindle struts.
  
• The tires are N-rated Bridgestone S-02 in stock sizes (205-16 and 225-16) with 29psi front and 34 rear.
  
• I'm running the Quaife Quick Rack, 2.5 turns lock-lock. Steering is smooth as silk, no play or binding.
  
• The ride heights are set to 24.75” front and 24.25” rear.
  
• Professionally aligned at Porsche by my usual tech, specs below.

The problem:

Earlier this fall I went on a 3-day trip with our Porsche Club, and we did some spirited drives on small roads. Tight turns, and uneven pavement. The steering is comfortable on more “normal” 2-lane roads, but as the speeds increase and turn radius decreases, the car becomes a real workout to drive. Very heavy steering. This trip included a passenger and luggage. I usually drive alone but with a passenger and the new rack I struggled to keep up with the other cars which was a frustrating experience. I'm probably chickening out more then the other drivers, but was still pushing harder then I usually do.

I know that someone will be quick to blame the Quaife rack. This is certainly contributing to the high steering effort, but its just great on regular 2-lane roads. What about my setup and the alignment specs? (I just don’t know enough about this stuff so I need some good guidance here please.)

Any tips would be greatly appreciated!

http://forums.pelicanparts.com/uploa...1539960781.jpg

As she sits:
http://forums.pelicanparts.com/uploa...1539960499.jpg

Pretty car.

I don't see anything wrong with the alignment that would increase steering effort.

Caster would be the one to look at for steering effort. Sort of like a caster on a shopping cart, the end result is self-centering. On a car, it's the "layback" angle of the steering axis. Think of a chopper motorcycle where the forks are real long, that a LOT of caster. Where the axis intersects the ground compared to where the contact patch is determines the amount of self-center. More caster = the wheel wants to go back to straight more.

911s have quite a bit of caster, but it's not super adjustable so you can't really wreck anything by being a little off. Technically your car is listed as out-of-spec low on caster, but I don't think a 911 can physically be at 6° so I think the measurement is wrong.

Just out of curiosity, you're not running any spacers up front or anything, are you? Those are factory wheels (or at least factory offsets)?

The updated castor settings look good at 6'15* and 6'22*.

A full tank of gas as well as a front boot loaded with luggage will certainly take away from the light steering feel.

You can go up to about 5.8 deg front castor. But that might make the car feel nervous at speed. I typically do not exceed 6.0 deg.

IMO you should also add some rear toe-in and front negative camber. The rear will feel more stable and steering will be sharper for sure

Since your car is so low, adding travel weight to the front will make it lower. This will increase castor and make steering more heavy (combination of weight and alignment.

How does the car ride unloaded?

Tire age? Tire pressure’s? Did you play with tire pressure due to added weight?

One of the references I always suggest is Puhn's How to Make Your Car Handle. Relatively inexpensive and a good reference. I have recommended it for a really long time. The car on the cover has some significant local history...

If you still lived here I'd invite you over and we'd set up your car in my garage...

At some point, you may need to decide what "type" of alignment specs that you want to run. You have obviously invested a lot of time and money and are very meticulous in your approach to developing your car.

I view alignment specs along a continuum, based on use case. One one end is bone stock daily driver, save the tires, et cetera.

On the other end, for example on an SC, might be based on trying to win at some type of competition, so fully optimized for a particular type of tire (brand, compound-- all of the details) and even a particular type of track. And even the weather! Lots of variables!

What I might suggest that you consider is to further define your use case.

For example, you might say "spirited driving and maybe an occasional competitive event like an AX or tarmac rally, but I don't want to destroy my tires for normal street driving of about 10 km per year."

Great settings for 911sc's have been around for a really, really long time. In my PCA literature archives (which go back 30 years) there are plenty of articles by folks like Bruce Anderson and Allan Caldwell that provide suggestions for use cases like my example above.

If I recall correctly, camber settings in many of these articles were at least a degree in front and maybe a bit more in the rear. Rear toe is usually about 1/16" in (1/32" per side).

I have used that rear toe setting on all of my 944 and 951 street/track and race cars, and I use it on my current 911 race car, which runs 16 inch diameter, 14 inch wide slicks.

In my experience, front toe settings for a use case like my example, are typically something like 1/16" toe out per side. That is what I have run on all of my Porsches with use cases like my example above. I even run that setting on the front of my 911 race car.

One way to dial in a mixed use car might be to set it up for AX, drive it at a few AX events, and once you are happy with the handling, then decide if you want to back it off a bit.

It is not difficult to learn how to do alignment yourself, especially at the front of the car.

Some of my favorite tools are the SmartCamber and SmartStrings Products created by former Lizard's chief engineer Craig Watkins. Craig is a long time PCA member and still races here locally. I use the SmartCamber, and made my own custom version of SmartStrings.

Even if you don't buy either right away, you may be able to download the instructions-- they are well written, and along with the Puhn book may help demystify the process of getting her dialed in.

Just guessing, from an armchair on another continent, is that considering the car was set-up, corner balanced to a certain weight, THEN you added a lot of weight: passenger and a full trunk ...it's going to perform differently. Sports cars are sensitive to weight gains and losses, you just feel it more now since every thing is set up the way it is.. again, just a guess. What I don't have to guess about is the gorgeousness of that Minerva Blue, almost like the "Estoril" on my M3. Stance looks great too. Take a drive with the weigh out, on similar roads and see if it is still an issue. Have friend drive it and see what they can tell you as you ride 'shotgun'. Either way get back to us on what you find out. My SC is going to have the same goodies when it's done, minus the Quaife rack and the gorgeous color.

All of the above is good advice, but not much addresses the change in steering effort. Just to be clear, the steering effort was fine before the upgrades?

My car is a bear to park with the 9" wide wheel / 255 RE71s up front but it gets much easier when I pop the 7" fronts back on, easier still when I put the storage all-season tires on. Still lightens up to tolerable above parking lot speeds.

IMO, anyone quick to blame the quick rack is on the right track. ;)

It's a great upgrade and I personally love it in all turns, but it does add more steering effort than any of your other upgrades. I'm not surprised you are finding it a bit harder to drive tight twisties on the street, where you aren't going very fast or reaching the limits of adhesion, lifting a wheel, transferring weight, etc.

I would add some toe and camber up front to let the car rotate a little easier, but be careful that you test the result on all the roads you plan on driving. It's pretty easy to make some small modifications at home and test-drive the result; you can always have your wrench dial it in on the rack once you show him in which direction you want to take it.

Have fun with it -- these cars are really rewarding to experiment with. :)

It says you came in with nearly zero caster, was that a random result after the suspension upgrade (put the new parts on, and button it up just enough to get to the alignment rack), or did you drive it much like that before getting the alignment done? Maybe you got used to that feeling (which would have been incredibly touchy...) which means ANY caster would make the car feel heavy.

Good advice, I like zero toe to a little toe out and I would bump up the front tire pressure, should make the front dance.

I am going to ask some dumb questions.

What kind of steering wheel do you have? Is it aftermarket and if so what is the diameter? When I replaced the factory steering wheel with the smaller diameter Prototipo the steering effort increased.

Are you running any spacers as Driven97 asked? I used to have spacers on my 16s. When I switched to 17x7.5 & 9s the steering effort decreased. I think this was because of scrub radius but I don’t think I could explain it as well as Mr. Verberg. I think it has to do with contact patch size and the scrub radius was improved with the right offsets (no spacers).

I will also add that I recently drove another Pelican’s widebody and I was amazed at how his steering felt easier than mine.

I’ve done most of the exact same things as you have.

Factory Fuchs 7" and 8" widths, no spacers front, 7mm rear. Thanks for the caster explanation!


Jamie, do you think I need to raise the ride height? I haven't driven the same roads so hard without a passenger with the quick rack, but unloaded on normal roads it feels pretty good. I'll look at the toe and camber!


29F 34R as above. Tires are 2.5 years old.


Lots of great input-- thank you! I'll look for the Puhn book. I don't care about tire life as I only drive the car a coulple thousand miles a year, so good sharp handling is a goal, without the car being nervous. Wish I could just drop by...


This makes complete sense. Either the wife needs to pack less shoes next time or stay home. Or the setup needs to accomodate the wife and her shoes!

Thanks! I love it. The paint is trashed but the money hasn't been used on the outside of this car. :)


I forgot to mentiion that the ER upgrades have been on the car for 3 seasons, just this past summer was the first season with the quick rack. The suspension was setup by the same guy after the ER install and again after I upgraded the rack. The car also got about 50-60 lbs lighter with removal of AC and CIS so needed a full adjustment. The steering effort seemed normal before, and seems normal now... right up until I push the car hard on really small roads with a passenger.


Thanks! I've got some settings to play with I think. Thing is I like the quicker steering on better roads without a passenger. Bit of a dilemma.


I can't explain the wacky initial settings. The ER upgrades went on two years ago and the car was aligned and setup then. Only suspension-related change after that was the rack install.


Thanks!


As long as your usual sense of humor is present, you can ask as many dumb questions as you want!

I have the stock station wagon cheap $hit plastic thing from 1981. Planning on a Moto Lita, but that will have to wait.

7mm, only in the rear, Stock Fuchs in 7' and 8" which I've had a couple years.[QUOTE]



Thanks everyone for the nice comments about my car, and all the great input. It would be good to get an old school 911 guy to drive my car and critique the handling. It could be I just suck and need driving school... anyway, that will have to wait for spring. I'll get to doing some reading about suspension setups.

The steering rack is the biggest issue

but things that would help

more front neg camber, up to ~-1° and less rear camber down to -1° 10'

less front toe 0°

less front caster, down to ~5°

remove the rear spacers, possibly add front spacers

more front tire pressure & less rear

add a front lip spoiler

Not sure if i'm reading your chart correctly , but does it indicate toe out in the rear as well ?
I have 1/8 total toe out on the front and 1/32 toe in on the rear of both my 911
and my race car ...

Just curious ?

My SC had a similar setup throughout the years, Elephant stuff, hollow torsions same effective as yours, the experimental ASP spring plates, Carrera sways too. It was setup as dual-purpose street and DE. When I drove it with 7 and 8's seemed to have great grip but heavy steering. 9's on the rear and a locking diff seemed to make it worse with respect to the heavy steering. I then went back to 15s both street and track sets, the steering improved significantly.

So, my -> thoughts <- are that with the front-loaded with baggage and fuel, a passenger and stock tire pressures, the fronts tire patch is bigger, sidewalls softer with broken in tires, and is creating more friction? As someone above suggested, you may want to try less rear, more front pressure - it's free, load up and give it a whirl. Although you lost weight by removing AC/CIS, I didn't read that the front has really changed much weight-wise. Your corner balance fixed it for normal payload but probably not helping with the front fully loaded with baggage, fuel, and passenger.

I didn’t see you mention a bump steer kit in your suspension upgrades.
If you raised the spindles 30mm, you either need to bend the arms a like amount, or use a deluxe bump steer kit with the dropped outer tie-rod ends.

This makes a huge difference in steering feel and kickback.

I’ll echo the others on the negative camber up front. I’d want -1 degree at least.

With basically zero camber up front, you are rolling onto the outer edge of your outside front tire in hard cornering, and that transfers considerable leverage against the steering.
These cars already have a positive scrub radius, and the dynamic scrub radius gets even worse in hard corners.
Also the more front swaybar you have, the worse it gets.

Thanks Bill! I'll definitely look at some changes. I may go back to the OEM rack as well. Would you also suggest raising ride height at all?

EDIT: The numbers are positive for toe both front and rear, which means toe-in in both cases. I had a good discussion with my tech and he says that front toe-out will make the car turn well but at the expense of straight-line stability.


Yeah, the added weight combined with the other factors is a recurring theme here. FWIW I also have the factory LSD which I just rebuilt to 80%. According to Matt at Guard even set up that way it isn't really 80%. In normal driving I don't notice it.


I forgot to mention the the ER racing spindles come with their bump steer kit as a package, so I'm set there. The bump steer isn't bad at all.

I've got to look at that camber setting for sure, thanks for the explanation!

As Tyson mentions I suspect some bump steer here, it will generally be it's ugliest on tight bumpy roads and hide a bit on smooth roads

So yes it's possible that the ride height needs to be adjusted, but i sort of discarded that because of the raised spindles.

It might be worthwhile to do a bump curve and possible adjust the steering arm ends to minimize bump steer or just live w/ it and not do the type of driving that causes the issues.